1. Field of the Invention
The present invention relates to an automatic pressure control for an end-face seal plate in seal mechanism of a high pressure steamer for wet-heat treatment of a textile product, in which the end-face seal plate is controlled automatically in accordance with the thermal expansion of seal rolls, incorporated in the seal mechanism, in order to create a constant sealing effect with a prescribed amount of pressure.
2. Description of the Prior Arts
A known seal mechanism for a high pressure steamer comprises an end-face seal plate for sealing the openings formed by a pair of seal rolls, their end-faces and the end face of a seal frame. For the purpose of making a close contact of said end-face seal plate with the end faces of the seal roll and the seal frame effectively, the present invention offers an automatic pressure control apparatus for the end-face seal plate. This apparatus enables the end-face seal plate and the end faces of the seal rolls and the seal frame to have close contact to each other automatically and effectively in accordance with the thermal expansion of the seal rolls incorporated in the seal mechanism. These seal rolls and the seal frame attached to the seal mechanism are heated to a tolerable degree in service so as to cause thermal expansion of the seal rolls and the seal frame. If the end-face seal plate is arranged closely in contact with the end faces of the seal rolls and the seal frame before putting in service, the operation becomes impossible due to an abnormal friction force caused by thermal expansion during the operation, but if a gap is provided previously between these fittings in anticipation of expansion, the pressure in the interior of the steamer body can hardly be raised to a prescribed value and needs a long period of time before it can reach a normal operation state.
To solve such drawbacks as the above-mentioned, the present inventors have recently proposed a seal mechanism comprising a pair of seal rubber rolls arranged above a hole of the high pressure steamer body through which the cloth is passed for the purpose of sealing the hole, seal frames for supporting these rolls to be freely rotatable, and an end-face seal plate pressedly in contact with the end faces of the seal rubber rolls and the seal frame; an automatic pressure control apparatus for the end-face seal plate comprising a press-down rod for causing the pressed contact of said end-face seal plate with the end-faces of the seal rubber rolls and the seal frame, a pressure responsive mechanism to push the press-down rod in the direction forward the end faces of the seal rubber rolls and the seal frame in cooperation with the inner pressure of the high pressure steamer body, and a plurality of springs for pressing down the end-face seal plate to the end faces of the seal rubber rolls and the seal frame with an appropriate pressure in case the pressure responsive mechanism is non-operative. In this apparatus, since the end-face seal plate is moved due to the inner pressure of the steamer body, the contact pressure between the seal rubber rolls and the end-face seal plate is elevated, as the inner pressure of the steamer body increases. On the other hand, the immediate reason for the change in the contact pressure between the seal rubber rolls and the seal end-face plate in the course of operation of a high pressure steamer is the thermal expansion of the seal rubber roll and the end-face seal plate. Accordingly, even when the pressure of the steamer body is increased, the contact pressure between the seal rubber rolls and the seal end-face plate becomes insufficient in a case where the degree of thermal expansion of the seal rubber rolls and the end-face seal plate is small, thus causing the problem of pressure leakage.